1. Field of the Invention
Embodiments of the invention relate to the field of microelectronic technology, and particularly relate to a substrate etching method.
2. Description of the Related Art
With MEMS (Micro-Electro-Mechanical Systems) devices and MEMS systems being widely used in the fields of automobile and consumer electronics, and the broad prospect of TSV (Through-Silicon Via) etching techniques being used in the future packaging field, a Dry Plasma Deep Silicon Etching Process gradually becomes one of the hottest processes in the MEMS processing field and TSV technique.
The major difference between the deep silicon etching process and common silicon etching processes lies in that the etching depth of the deep silicon etching process is significantly larger than that of a common silicon etching process. Generally, the etching depth of the deep silicon etching process is tens of micrometers, or may be up to a hundred micrometers, while the etching depth of a common silicon etching process is less than 1 micrometer. To etch a silicon material with a thickness of tens of micrometers, the deep etching process is required to have a faster etching rate, a higher selectivity ratio and a larger aspect ratio.
At present, a mainstream deep silicon etching process is the Bosch process invented by Robert Bosch GMBH, Germany, or its optimizations, which have the main feature that the whole etching process is a process in which a single cyclic unit including an etching operation and a deposition operation is repeated multiple times, i.e., the whole etching process is cycles of the etching operation and the deposition operation. In this case, the process gas adapted for the etching operation is SF6. Further, in the process of performing the etching operation, in order that more active radicals can be generated to improve the etching rate of the process gas on a silicon substrate, the chamber pressure generally needs to be kept at a relatively high level throughout the process of performing the etching operation. However, this will lead to such a problem that the generated reaction products after etching can hardly be discharged from a silicon groove, so that the reaction products accumulated within the silicon groove damage a side wall of the silicon groove, the side wall of the silicon groove thus has a rough profile, which in turn causes the result of the etching process not ideal.